Valve-operating mechanism for internal combustion engines



Jan., 24, w67 R. BERTSCH ETAL 3,299,870

VALVE-OPERATING MECHANISM FOR INTERNAL COMBUSTION ENGINES Filed Jan. 2l,1966 2 Sheets-Sheet l Q5 we w* .n is

J., 24, 1967 R. BERTscH ETAL 3,299,870

VALVE-OPERATING MECHANISM FOR INTERNAL COMBUSTION ENGINES Filed Jan. 2l,1966 2 Sheets-Sheet 2 "3% i HI u i Y 'lg-f5 United States Patent O3,299,870 VALVE-OPERATENQ MECHANESM FOR HNTERNAL COMBUSTEON ENGENESRichard Bertsch, Asperg, and Josef Heinzelmann, Ab-

iach, near Sigmaringen, Germany, assignors to Robert Bosch G.m.b.H.,Stuttgart, Germany Filed Jan. 21, 1966, Ser. No. 522,2l7 Claimspriority, application Germany, Feb. 6, 1965, B 80,405 9 Claims. (Cl.12d-90) The present invention relates to valve-operating mechanisms forinternal combustion engines, and particularly to improvements inhydraulic valve tappet mechanisms. Still more particularly, theinvention relates to improvements in hydraulic valve tappet mechanismsof the type which are provided with automatic valve clearanceeliminators, also called lash eliminators.

lt is already known to provide a valve tappet mechanism with a valvewhich permits outflow of some oil from the chamber of the lasheliminating unit and to use such oil to lubricate certain relativelymovable parts of the valve-operating mechanism in which the tappet isput to use. The valve acts not unlike a throttle and cannot completelyprevent escape of oil from gthe chamber. The chamber of the lasheliminating unit normally receives oil through a large number of inletswhereby the oil escapes when the engine is idle so that the chamber islled with air. The escaping oil can contaminate the interior of theengine. Also, it 4takes about 15 minutes to rell the chamber with oilwhen the engine is restarted whereby the mechanism rattles and produceswhat is known as tappet noise. Furthermore, and since oil which is usedto lubricate the moving parts of the valve-operating mechanism is notsupplied in metered quantities, it happens again an-d again that theparts which require lubrication receive too much oil or too little oil.Both such extremes are undesirable, particularly excessive lubricationbecause surplus oil is supplied at the expense of other lubricantconsuming stations. Freely floating lubricant admitting valves arelikely to jam and to either prevent satisfactory lubrication or topermit excessive lubrication each of which may cause serious damage tothe engine. Proposals to admit lubricant through a hollow push rod andtoward the tappet also have met with little success because the rockerarm at the remote end of the push rod is disstant from the customary oilcirculating system of the engine so that the introduction of oil intothe remote end of the push rod necessitates the provision of specialconduits with attendant increase in cost and other inconveniences. In amanner well known from the art of valveoperating mechanisms for internalcom-bustion engines, the push rod has one of its ends journalled in acup of the tappet and its other end transmits motion to a rocker armwhich, in turn, effects seating and unseating of an exhaust valve oranother valve which regulates the flow of uids to or from the cylinderof an engine.

It is now an important object of the present linvention to provide animproved valve-operating mechanism for internal combustion engineswherein the tappet is constructed and assembled in such a way that thechamber of the lash eliminating unit cannot receive air and wherein thetappet simultaneously insures proper and fully controlled lubrication ofthe push rod and, if necessary, of certain other movable parts in theengine.

Another object of the invention is to provide a mecha- 3,299,870Patented Jan. 24, 1967 ICC nism of the just outlined characteristicswhich can be readily connecte-d in the oil circulating system of aconventional internal combustion engine and wherein such connectionnecessitates the provision of very short oil conveying passages.

A further object of the invention is to provide a hydraulic valve tappetwhich can control the admission of lubricant to the push rod with utmostaccuracy, in automatic response to starting of the engine, and at a ratewhich remains constant for any desired length of time and at differenttemperatures.

An additional objects of our `invention is to provide a tappet whoseoperation is noiseless, wherein such noiseless operation is insured atall times whenever the engine is in operation and immediately after theengine is started, and which consists of a small number of relativelysimple and compact parts.

Still another object of the invention is to provide a hydraulic valvetappet wherein the chamber of the lash eliminating unit is invariablyand fully sealed from the system which admits metered quantities oflubricant to the cup or cups for the push rod and wherein the chamber isnot likely to receive air when the valve-operating mechanism is inworking condition.

A concomitant object of the invention is to provide a hydraulic valvetappet which can be readily substituted for the tappets of presentlyknown valve-operating mechanisms for use in internal combustion engines.

Briey stated, one feature of our present invention resides in theprovision of a valve-actuating mechanism, particularly for use ininternal combustion engines. The mechanism comprises a driven cam whichrotates about a fixed axis, a housing adjacent to the cam and having aguide bore therein and an oil supply channel which is permanently filledwith lubricant and communicates with the guide bore, a hydraulic valvetappet including a hollow cupped body reciprocably received in the guidebore of the housing and having an end Wall in motion-receivingengagement with the cam, a lash-eliminating plunger reciprocablyreceived in the body Iand defining with the end wall a compensatingchamber, a second chamber provided in the plunger and communicating withthe cornpensating chamber, a cup rigid or integral with the plunger anddefining a `socket which faces away from the end wall of the body, andone-way valve means provided 'between the two chambers for admitting oilfrom the second chamber to the compensating chamber, and a push rodhaving an end portion extending int-o the socket and arranged to biasthe plunger in a direction toward the end wall and to thereby maintainthe end wall in permanent motion-receiving engagement with the cam. Thebody and the plunger of the valve tappet dene a first passage whichestablishes a permanent connection between the oil supply channel andthe second chamber and a second passage for admitting oil from thechannel to the socket. The rst passage includes a single inlet to thesecond chamber and the second passage is preferably` municates with itssocket (and hence with the axial bore of the push rod) and serves toadmit oil to the periphery of the shaft so that the latter is properlylubricated in response to reciprocation of the valve tappet body.

The novel features which are considered as characteristic of theinvention are set forth in particular in the appended claims. Theimproved valve-operating mechanism itself, however, both as to itsconstruction and its mode of operation, together with additionalfeatures and advantages thereof, will be best understood upon perusal ofthe following detailed description of a specific embodiment withreference to the accompanying drawings, in which:

FIG. 1 is a fragmentary section through an internal combustion engineand illustrates a portion of a valveactuating mechanism which embodiesour invention;

FIG. 2 is a section as seen in the direction of arrows from the lineII--II of FIG. 1 and shows two adjoining tappets; and

FIG. 3 is an enlarged axial sectional View of the tappet which is shownin FIG. 1.

Referring rst to FIG. l, there is shown a portion of an internalcombustion engine embodying a valve-operating mechanism which includesthe improved hydraulic valve tappet 2. This tappet comprises a cuppedcylindrical b-ody 27 which is reciprocable in a guide bore 18 machinedinto the housing 1 of the internal combustion engine. The end wall 28 ofthe body 27 abuts against and receives motion from a cam 3 which ismounted on a driven cam shaft 4. A cup 36 of the tappet 2 defines asocket or seat 48 (see FIG. 3) which receives one end portion 14 of anelongated hollow push rod 5. The other end portion 13 of the push rod 5is free to swivel in a socket 12 provided at one end of a leg 6 formingpart of a rocker-arm 7 which is rockable on a rocker arm shaft 7a. Theother leg` 8 of the rocker arm 7 carries an adjustable motiontransmitting `screw 8a which abuts against the stem 9aof a valve member9 forming part, for example, of an exhaust valve for the cylinder of theinternal combustion engine. The screw 8a actually bears against afollower 9b which constitutes a retainer for one end of a helical valvespring 9'. The other end of the spring 9' bears against a stationarypart 1a of the housing 1'so that this spring normally tends to maintainthe valve member 9 in sealing engagement with its seat 1b. At the sametime, the spring 9' biases the push rod I ina direction to the left, asviewed in FIG. 1, whereby the end wall 28 of the valve tappet body 27bears against the face of the cam.3. The leg 6 of the rocker arm 7 isformed with a b-ore 11 which communicates with the axial bore 15 of thepush rod 5 viasocket 12 and conveys lubricant to the bore of the rockerarm, i.e., to the periphery of the rocker arm shaft 7a. The end portions13, 14 of the push rod 5 are of substantially semispherical shape andthe ends of the bore 15 in the push rod 5 are conhgurated in such a waythat this bore is in permanent communication with the `bore 11 as wellas with a bore 49 (see FIG. 3) which forms part of a passage forconveying lubricant to the socket 48 of the cup 36.

The oil is supplied by an oil supply channel 16 which is machined intothe housing 1 and which is connected to the oil circulating system ofthe engine. FIG. 1 shows that the channel 16 communicates with the guidebore 13, and FIG. 2 shows that this channel 16 can supply oil to aplurality of tappets including the tappet 2 and a second tappet 2', thelatter being reciprocable in a second guide bore 17 of the housing 1 andreceiving moti-on from a second cam 3' on the cam shaft 4. The tappet 2transmits motion to a second push rod 5', and is external surface 19 isformed with two adjacent butV spaced circumferential grooves 21, 22respectively communicating with radially inwardly extending bores 25',26'. Since the construction of the tappets 2, 2' is identical, FIG. 3merely shows the details of construction of the tappet 2. Thesoledierence between the two tappets is that they move with reference toeach other because the angular position of the cam 3' is different fromthat of the cam 3. The external surface 20 of the tappet 2 (i.e., of itsbody 27) is formed with two circumferential grooves 23, 24 whichrespectively corresponds to grooves 21, 22, and with two radial bores25, 26 which respectively correspond to the bores 25', 26'. The oilsupply channel 16 is substantially normal to the guide bores 17, 18 andis in permanent communication with the groove 23 (and also with thegroove 21). The cylindrical portion -or skirt of the body 27 shown inFIG. 3 accommodates a reciprocable plunger 29 which is rigid with thecup 36 whereby the socket 48 of the cup 36 faces away from the end wall28 of the body. The spring 9 shown in FIG. 1 biases the plunger 29 in adirection to the left, as viewed in FIG. 3. The left-hand end face 30 ofthe plunger 29 defines with the bottom wall 28 a compensating chamber 31which forms part of the lash eliminating unit and is always lled withoil. This chamber 31 communicates with a second chamber 38 which isformed in the plunger 29 and one end of which is sealed by the cup 36.

The plunger 29 is sealingly telescoped into the bore 33 of the body 27,and its external surface 32 is formed with two peripheral grooves 34, 35which respectively communicate with the bores 25, 26. The grooves 34, 35are outwardly adjacent to the cup 36 which abuts against an internalshoulder 37 of the plunger 29. The periphery of the cup 36 is providedwith two grooves 45a, 46a which respectively communicate with thegrooves 34, 35 through the intermediary of radial bores 45, 46 providedin the plunger 29. The cup 36, which can be considered as constituting acomponent or integral part of the plunger 29, is formed with an inclinedbore 47 which connects the groove 45a with the second chamber 38, andwith the radially extending bore 49 which connects the groove 46a withthe socket 48. The groove 34, the bore 45, the groove 45a and the bore47 together constitute a single inlet to the second chamber 38, and thisinlet forms part of a first passage which further includes the groove 234and the bore 2S and serves to permanently connect the oil supplychannel 16 with the chamber 38. The second passage includes the groove24, the bore 26, the groove 35, the bore 46, the groove 46a and the bore49, and the function of this second passage is to intermittently connectthe oil supply channel 16 with the socket 48 and hence with the axialbore 15 of the push rod 5.

A one-Way ball valve 39 controls the how of oil between the chambers 31and 38 in such a way that oil can ilow from the chamber 38, through aconnecting bore 40 in the left-hand end portion of the plunger 29,v andinto the chamber 31 but not in the opposite direction. The valve 39comprises a spherical valve member 42 which is biased against its seatthe left-hand end of the bore 40 by a valve spring 41 mounted in a cage43 which is biased against the plunger 29 by a strong helical expansionspring 44. The spring 44 is accommodated in the compensating chamber 31and -operates between the end lwall 28 and an outwardly extending angeof the cage 43.

The internal surface surrounding `a counterbore 50 at the right-handaxial end of the body 27 is formed with an annular groove for aretaining ring 51 which acts not unlike a stop and serves to prevent theplunger 29 from moving too far away from the end wall 28. The endportion 14 of the push rod 5 extends through the counterbore 5t) and isfree to swivel in the socket 48 of the cup 36. The ring 51 lalsoprevents the plunger 29 from falling out during assembly of the tappet2.

The valve-operating mechanism of our invention operates as follows:

When the engine is running, the supply channel 16 is filled with oilwhich is maintained under pressure by the lubricating pump, not shown.The axial length of the groove 23 in the peripheral surface 26 ofthe-tappet body 27 is selected in such a way that the bore 25 is inpermanent communication with the channel 16. The same holds true for thegroove 34 and bore 45 so that the chamber 38 is permanently filled withoil entering through the inlets 34, 45, 45a, 47. The engine drives thecam shaft 4 so that the cam 3 rotates and cooperates with the valvespring 9 to reciprocate the tappet 2 whereby the latter causes the valvemember 9 to move away from its seat 9b when the push rod 5 moves in adirection to the right, as viewed in the drawings. As stated before, theaxial length of the lgroove 23 is such that the bore 25 remains inpermanent communication with the channel 16 despite the fact that thetappet 2 reciprocates in the guide bore 18 of the housing 1. Whenevernecessary, the one-way valve 39 admits oil from the chamber 38 into thechamber 31 to make sure that the tappet will operate without lash. Thevalve 39 admits oil to the chamber 31 when the plunger 29 moves awayfrom the end wall 28 of the body 27. The axial length of grooves 34, 35in the peripheral surface 32 of the plunger 29 is such that thesegrooves remain in communication with the bores 25, 26 even if theplunger changes its axial position with reference to the body 27. As arule, the plunger 29 will be free to perform strokes of up to 4 mm. sothat the effective length of the tappet 2 (between the outer side of theend wall 28 and the bottom zone of the socket 4S) may be varied by thesame distance.

While the channel 16 remains in permanent communication with the chamber38 in the plunger 29, the socket 48 receives oil intermittently inresponse to rotation of the cam 3 and in response to resultingreciprocation of the tappet 2. In FIG. 3, the groove 24 is shown in an`axial position in which it cannot communicate with the channel 16.However, when the tappet 2 is shifted by the lobe of the cam 3 to assumean axial position corresponding, for example, to that of the tappet 2shown in FIG. 2, the groove 24 will communicate with the channel 16 andwill admit oil to the bore 49 and socket 48. The bore 49 may receive oilduring about one-seventh (about 50) of each full revolution of the cam3. The amounts of oil which are admitted to the socket 48 are accuratelymetered and the metering of oil is not affected by changes intemperature. The second passage including the groove 24 and bore 49throttles the flow of oil to the socket 48, and the rate at which thesocket 48 receives oil is properly related to the rotational speed ofthe cam shaft 4.

The oil which is discharged from the bore 49 lubricates the end portion14 of the pushrod 5 and also fiows through the axial bore to lubricatethe socket 12. Some such oil ows further through the bore 11 of the leg6 and lubricates the surface surrounding the bore 10 of the rocker arm 7as well as the periphery of the rocker arm shaft 7a. If desired, the leg8 of the rocker arm 7 may also be provided with a bore (indicated at11a) which can convey lubricant all the way to the valve spring 9.

A very important advantage of the improved tappet is that the chamber 38of the plunger 29 is sealed against entry of air, even when the engineis idle for extended periods of time. This is due to the fact that thechamber 38 is provided with a single inlet including the inclined bore47, and also :because the chamber 38 is invariably sealed from thesocket 48. The two passages which respectively convey lubricant to thechamber 38 and socket 48 are very short so that proper lubrication ofthe push rod 5 and proper operation of the lash eliminating unit canbegin in immediate response to starting of the engine.

Without further analysis, the foregoing will so fully reveal the gist ofthe present invention that others can, by applying current knowledge,readily adapt it for various applications without omitting featureswhich fairly constitute essential characteristics of the generic andspecific aspects of our contribution to the art and, therefore, suchadaptations should and are intended to be comprehended within themeaning and range of equivalence of the following claims.

What is claimed as new and desired to be protected by Letters Patent is:i

1. In a valve-operating mechanism for internal combustion engines, adriven cam; a housing adjacent to said cam and having a guide boretherein and an oil supply channel communicating with said bore; a valvetappet including a hollow body reciprocably received in said bore andhaving an end wall in motion-receiving engagement with said cam, alash-eliminating plunger reciprocably received in said body and definingwith said end wall a compensating chamber, said plunger further having asecond chamber communicating with said compensating chamber and a cupdefining a socket facing away from said end wall, and one-way valvemeans provided between said chambers for admitting oil to saidcompensating chamber; and a push rod having an end portion extendinginto said socket and arranged to bias said plunger in a direction towardsaid end wall, said body and said plunger defining a first passagepermanently connecting said channel with said second chamber and asecond passage for admitting oil from said channel to said socket, saidsecond passage being in permanent communication with said socket and inintermittent communication with said channel in response toreciprocation of said body.

2. A structure as set forth in claim 1, wherein said first passageincludes a single inlet to said second chamber.

3. A structure as set forth in claim 2, wherein said second chamber isadjacent to said cup and is permanently sealed from said socket, saidinlet including a single bore extending from said second chamber towardthe periphery of said plunger.

4. A structure as set forth in claim 3, wherein said first passagefurther includes a bore provided in said body and connecting said inletwith said channel.

5. A structure as set forth in claim 4, wherein said first passagefurther includes a circumferential groove provided in said plunger andconnecting said inlet with the bore of said body in each axial positionof said plunger with reference to said body.

6. A structure as set forth in claim 1, wherein said second passageincludes a peripheral groove provided on said body and movable into andfrom registry with said channel in response to reciprocation of saidbody, a bore provided in said body in permanent communication with saidgroove, a second peripheral groove provided on said plunger in permanentcommunication with said bore, and a further bore provided in saidplunger to connect said second peripheral groove with said socket.

7. A structure as set forth in claim 1, wherein said push rod has anaxial bore communicating with said second passage and comprises a seconden-d portion distant from said tappet, and further comprising a shaftand a rocker arrn mounted on said shaft, said rocker arm defining asocket for the second end portion of said push rod and having a boreconnecting the bore of said push rod with the periphery of said shaft sothat the shaft is lubricated in response to admission of oil from saidchannel to said second passage.

8. A structure as set forth in claim 1, wherein each of said passagescomprises a circumferential groove provided on said body, a peripheralgroove provided on said plunger, and a radial bore connecting thecircumferential groove with the peripheral groove, said inlet being inpermanent communication with the peripheral groove of said first passageand the circumferential groove of said first passage being in permanentcommunication with said channel, the circumferential groove of saidsecond passage being movable into and out of registry with said channelin response to reciprocation of said body and said second passagefurther including bores provided in said plunger and in said cup toestablish a permanent communication between said socket and the 7 '8peripheral groove of said second passage, said second 2,821,970 2/ 1958Line 123-90 chamber being permanently sealed from said socket. 2,874,6852/ 1959 Line 12S-90 9. A structure as set forth in claim 1, wherein said2,938,508 5/ 1960 Papenguth 123-90 cam is rotatable about a xed axis andfurther compris- 3,070,080 12/1962 Van Slooten y123-90 ing stop meansfor determining the maximum stroke of 5 3,111,119 11/ 1963 Bergmann123-90 said plunger in a direction away from said end Wall. 3,177,8574/1965 Kuchen et al. 12.3-90

References Cited by the Examiner MARK NEWMAN, Primary Examiner.

UNITED STATES PATENTS AL LAWRENCE SMITH, Examiner.

2,259,905 10/1944 Moncrieff 12s-9o 10

1. IN A VALVE-OPERATING MECHANISM FOR INTERNAL COMBUSTION ENGINES, ADRIVEN CAM; A HOUSING ADJACENT TO SAID CAM AND HAVING A GUIDE BORETHEREIN AND AN OIL SUPPLY CHANNEL COMMUNICATING WITH SAID BORE; A VALVETAPPET INCLUDING A HOLLOW BODY RECIPROCABLY RECEIVED IN SAID BORE ANDHAVING AN END WALL IN MOTION-RECEIVING ENGAGEMENT WITH SAID CAM, ALASH-ELIMINATING PLUNGER RECIPROCABLY RECEIVED IN SAID BODY AND DEFININGWITH SAID END WALL A COMPENSATING CHAMBER, SAID PLUNGER FURTHER HAVING ASECOND CHAMBER COMMUNICATING WITH SAID COMPENSATING CHAMBER AND A CUPDEFINING A SOCKET FACING AWAY FROM SAID END WALL, AND ONE-WAY VALVEMEANS PROVIDED BETWEEN SAID CHAMBERS FOR ADMITTING OIL TO SAIDCOMPENSATING CHAMBER; AND A PUSH ROD HAVING AN END PORTION EXTENDINGINTO SAID SOCKET AND ARRANGED TO BIAS SAID PLUNGER IN A DIRECTION TOWARDSAID END WALL, SAID BODY AND SAID PLUNGER DEFINING A FIRST PASSAGEPERMANENTLY CONNECTING SAID CHANNEL WITH SAID SECOND CHAMBER AND ASECOND PASSAGE FOR ADMITTING OIL FROM SAID CHANNEL TO SAID SOCKET, SAIDSECOND PASSAGE BEING IN PERMANENT COMMUNICATION WITH SAID SOCKET AND ININTERMITTENT COMMUNICATION WITH SAID CHANNEL IN RESPONSE TORECIPROCATION OF SAID BODY.